For months, political observers said over and over that the GOP front-runner wouldn’t win the nomination. But after accumulating seven more victories on Super Tuesday, bringing his total to 11 of the first 15 states, Donald Trump has destroyed that conventional wisdom and looks likely to be Hillary Clinton’s opponent in the fall.

And after getting it so wrong once, many prognosticators now seem worried about underestimating Trump’s chances in the general election. “Democrats to Clinton: Don’t laugh off Trump threat,” blared a Politico headline. “I’ve gone from denial,” Connecticut Gov. Dannel Malloy told the New York Times, “to admiration . . . to real worry.” Even Democrats projecting confidence about a Trump-Clinton matchup typically scramble to add an “on the other hand” disclaimer.

To borrow a phrase from one of the men trailing Trump: Let’s dispense with the notion that Trump has a real shot at winning in November.

Start with the basic electoral math. At the national level, Trump trails Clinton by more than three percentage points in the RealClearPolitics polling average, and she has led him in 15 of 17 national polls since December. Trump clearly does the worst against her of the possible Republican nominees. His unfavorables are historically high for a general election nominee. And if “more than three points” doesn’t sound impressive, note that Barack Obama rarely led Mitt Romney by more than three points in the polling averages — and he won easily. What state polling we have suggests that Clinton, like Obama, will start with 220 or 230 electoral votes safe or close to that amount, leaving Trump little room for error.